Hi!The code provided by the microchip for 3 Phase Induction motor control ,in this code they are using Sine look up, but from the code I don't understand that how they are taking the values for 3 phase which are 120 degree apart from each other from single Sine Look Up table which is from 270 degree to 90 degree with 10 Degree Resolution.They are using the 3 offset pointer for 3 phases but what is the method of taking 3 values with the help of offset register which are 120 degree apart from each other from single SIN look up Table.

Hi!Yes I really mean that how to look up a sine-table for 3-phase by the help of 19 values of Sin which starts from 270 degree and ends at 90 degree with 10 degree resolution.;*******************************************************************************;EQUATION USED FOR CALCULATION OF SINE TABLE ENTRIES = (SIN(ANGLE)+1)*FF/2;ANGLES ARE FROM 270 DEG. TO 90 DEG. STEP SIZE = 10 DEG.;*******************************************************************************Sine Table: RETLW 0X00 RETLW 0X01 RETLW 0X07 RETLW 0X11 RETLW 0X1D RETLW 0X2D RETLW 0X3F RETLW 0X53 RETLW 0X69 RETLW 0X7F RETLW 0X95 RETLW 0XAB RETLW 0XBF RETLW 0XD1 RETLW 0XE1 RETLW 0XED RETLW 0XF7 RETLW 0XFD RETLW 0XFFPlease explain me the method of taking "Set of 3 values of Sine" at a time, from the table given above, which are 120 Degree apart from each other without using trigonometric Sin function.

Posted on: May 28, 2009, 12:08:10 12:08 - AutomergedHi!These are the codes of 3 Phase induction Motor and they are using Sine Look Up table for taking "3 sin values" which are 120 degree apart from each other. Please have a look at this.